<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
 <head>
  <meta http-equiv="content-type" content="text/html; charset=UTF-8">
  <title>Stream Filters</title>

 </head>
 <body><div class="manualnavbar" style="text-align: center;">
 <div class="prev" style="text-align: left; float: left;"><a href="stream.constants.html">预定义常量</a></div>
 <div class="next" style="text-align: right; float: right;"><a href="stream.contexts.html">Stream Contexts</a></div>
 <div class="up"><a href="book.stream.html">Streams</a></div>
 <div class="home"><a href="index.html">PHP Manual</a></div>
</div><hr /><div id="stream.filters" class="chapter">
 <h1>Stream Filters</h1>

 <p class="simpara">
  A <em>filter</em> is a final piece of code which may perform
  operations on data as it is being read from or written to a stream.
  Any number of filters may be stacked onto a stream. Custom
  filters can be defined in a PHP script using
  <span class="function"><a href="function.stream-filter-register.html" class="function">stream_filter_register()</a></span> or in an extension using the
  API Reference in <a href="internals2.streams.html" class="xref">流的使用</a>.  To access the list of currently 
  registered filters, use <span class="function"><a href="function.stream-get-filters.html" class="function">stream_get_filters()</a></span>.
 </p>
</div>
<hr /><div class="manualnavbar" style="text-align: center;">
 <div class="prev" style="text-align: left; float: left;"><a href="stream.constants.html">预定义常量</a></div>
 <div class="next" style="text-align: right; float: right;"><a href="stream.contexts.html">Stream Contexts</a></div>
 <div class="up"><a href="book.stream.html">Streams</a></div>
 <div class="home"><a href="index.html">PHP Manual</a></div>
</div></body></html>
